Apparatus for moving wire

ABSTRACT

An apparatus for moving cylindrical members, particularly welding wire, includes a rotary to linear actuator having an axially extending opening through which wire is fed, at least a pair of opposed rollers mounted on the actuator body, the axis of each being skewed or inclined relative to the direction of wire feed, which rotate with the body to impart a component of force to the wire to move it linearly through the actuator. Each roller is carried by an arm pivotally mounted on the actuator body and each arm includes a centrifugal weight which forces the roller against the wire as the actuator is rotated. Biasing means, such as torsion bars or small springs assist in holding the rollers against the wire at low rotational speeds. The actuator may be rotated by a motor having an axially extending opening through its armature through which the wire may be fed to the actuator.

United States Patent 1 Karnes et a1.

[ APPARATUS FOR MOVING WIRE [75] Inventors: Donovan Karnes; Marion F.

Centliver, both of Troy, Ohio [73] Assignee: Hobart Brothers Company,Troy,

Ohio

[22] Filed: July 7, 1972 {21] Appl. No.: 269,721

Related U.S. Application Data [62] Division of Ser. No. 40,189, May 25,1970,

abandoned.

[52] U.S. Cl 226/168, 226/188 [51] Int. Cl B65h 17/24 [58] Field ofSearch 214/338, 339;

[56] References Cited UNITED STATES PATENTS 3,424,012 l/l969 Hirmann74/25 Primary Examiner-Richard A. Schacher Assistant Examiner-Gene A.Church Att0rney-Edward P. Forgrave June 12, 1973 57] ABSTRACT Anapparatus for moving cylindrical members, particularly welding wire,includes a rotary to linear actuator having an axially extending openingthrough which wire is fed, at least a pair of opposed rollers mounted onthe actuator body, the axis of each being skewed or inclined relative tothe direction of wire feed, which rotate with the body to impart acomponent of force to the wire to move it linearly through the actuator.Each roller is carried by an arm pivotally mounted on the actuator bodyand each arm includes a centrifugal weight which forces the rolleragainst the wire as the actuator is rotated. Biasing means, such astorsion bars or small springs assist in holding the rollers against thewire at low rotational speeds. The actuator may be rotated by a motorhaving an axiably extending opening through its armature through whichthe wire may be fed to the actuator.

8 Claims, 24 Drawing Figures Patented June 12, 1973 4 Sheets-Sheet lFIG-1 Patented June 12, 1973 3,738,555

4 Sheets-Sheet 2 FIG-6 35 FIG-7 8o g "O 71+ 1 90 FIG-13 Patented June12, 1973 3,738,555

4 Sheets-Sheet 3 l A B Patented June 12, 1973 4 Sheets-Sheet 4 FIG-22FIG-23 FIG-24 APPARATUS FOR MOVING WIRE RELATED APPLICATION Thisapplication is a division of application Ser. No. 40,189, filed May 25,1970 now abandoned.

BACKGROUND OF THE INVENTION In some welding situations, it is convenientto use a hand held welding gun which supplies a consumable welding wireat a controlled rate to the weld. Such guns may also include means forsupplying a shielding gas to envelop the weld and means for supplyingelectrical current to the consumable wire. One such welding gun is shownin U.S. Pat. No. 3,093,728.

Since the operator must hold the gun continuously during welding, it isdesirable that the gun be made as lightweight as possible. Also,reducing the size of the gun simplifies storage and handling.

In prior art welding guns, a consumable welding wire is usually passedbetween drive rollers, at least one of which is knurled and. driven byan electric motor. Frequently, the other roller is spring biased towardthe driven roller to insure that enough frictional force is available'tomove the wire. Thus, as the wire is initially fed into the gun, the biasof the springs must be overcome before the wire will pass between therollers. With this typeof gun, however, slippage between the rollers andthe wire tends to abrade the wire and remove its protective coating.Also, the residue from such abrasion may eventually cause a malfunctionof the gun.

SUMMARY OF THE INVENTION This invention relates to an improved apparatusfor moving small diameter cylindrical members and employs a novel rotaryto linear actuator. The invention is particularly useful in a weldinggun since it permits the gun to be lightweight and small in diameter tofacilitate use by the operator.

Rotary to linear actuators have been employed which use inclined contactrollers engaging a rigid cylindrical member. When the inclined rollersare rotated around the cylindrical member, they will follow a helicalpath relative to the member, and since the rollers are prevented frommoving in the axial direction, a part of the rotary motion is convertedto linear movement of the member. The greater the angle the axis of therollers make with respect to the axis of the cylindrical member, thegreater will be the linear velocity imparted to the cylindrical memberfor a given rotational speed. One such rotary to linear motion device isshown in U. S. Pat. No. 2,152,518.

In a preferred embodiment of this invention, the rotary to linear motionactuator includes a body having a wire receiving opening extending therethrough which is coaxial with its axis of rotation. At least a pair ofopposed rollers are mounted on the body in mutually opposed relation tothe opening and spaced radially from the axis of rotation of the body,with the axis of the rollers being skewed or inclined so that a portionof the rotary motion of the rollers around the axis of the body willimpart linear motion to a wire fed through the opening in the body. Therollers are carried by arms pivotally mounted to the actuator body, andeach arm includes a weight which, as the actuator body is rotated, willmove outwardly due to centrifugal force to force the rollers against thewire. Thus, as the actuator is rotated, a component of velocity isimparted by the rollers to the wire in the axial direction in directproportion to its rotational speedfln one preferred embodiment, twopairs of opposed rollers are used with each roller engaging the wire atapproximately intervals.

Biasing means assist in urging the rollers into positive contact withthe wire for initial starting and continued operation at low rotationalspeeds of the body. The biasing means may include small springs whichare positioned either between the actuator body and the centrifugalweights or between the weights on one arm and the roller supporting partof the arm supporting the other roller of the mutually opposed pair ofrollers. The biasing means may also include torsion bars pivotallysupporting the rollers and weight carrying arms with the torsion barsbeing arranged. to bias the rollers against the wire.

This invention is useful in many applications, such as a hand heldwelding gun or as a device for moving wire. For example, it may bedesirable to place a reel of wire at one location and move this wirethrough a substantial length of cable to another location. Sincefrictional forces increase with the length of'the cable, merelyproviding a source of motive force at either end of the cable may not besufficient to move the wire without damage. A wire feeding mechanism ofthe type described above could be installed at one or more intermediatelocations to provide the additional force neededto move the wire underthese circumstances.

It is desirable to maintain the wire in tension throughout the length ofthe cable due to the low column strength of small diameter wires, andfor this reason, the intermediate wire feeding mechanisms locatedclosest to the wire source are designed to move the wire at slightlyslower speeds than those located further from the wire source.

Also, the wire feeding apparatus of this invention may be designed sothat it will not damage the wire if the wire is restrained from movementwhile the rotary to linear actuator continues to rotate. In other words,an intermediate source of motive force could be run continuously, ifdesired, even though the wire may be stalled, thus eliminating the needfor extra switching circuits, or it may be operated as a constant torquedevice with appropriate electrical circuitry.

To prevent the wire from being distorted excessively or damaged as it ismoved by the actuator due to forces exerted by the rollers, the contactforce between the rollers and the wire is limited. The forces exerted bythe rollers on the wire are determined by the rotational speed of theactuator, the force of the biasing means, and by the contact areabetween each roller and the wire.

It has been found that in some situations, especially where it is notintended that the wire slip relative to the actuator, it is preferredthat the force exerted by the rollers be increased until some smallamount of yielding of the surface of the wire results at the point ofcontact between the rollers and the wire. As a result, the force movingthe wire in the linear direction exceeds that which would be expected ifonly the coefficient of friction between the wire and rollers isconsidered.

Sufficient force to move the wire is obtained by providing a pluralityof mutually opposed pairs of inclined rollers, thus distributing theforces along the wire. In order to obtain the sufficient driving forcefor wires having low tensile strength, such as aluminum, while at thesame time avoiding distorting or damaging the wire, several pairs ofmutually opposed, inclined rollers are used with each roller exertingless force than those rollers which are used to move steel wire. In thepreferred embodiment of the invention, four pairs of mutually opposedinclined rollers are used for steel while eight pairs of mutuallyopposed rollers are used to impart the same driving force to aluminumwire.

In a welding gun, a gas passageway for inert shielding gas is formed inthe gun housing to direct the gas around the motor and the rotary tolinear actuators. The gas flow will cool the motor and remove dirt andwire surface contaminates carried by the wire which may be knocked looseby the inclined wire engaging rollers and would otherwise build up inthe gun housing.

Accordingly, it is an object of this invention to provide an improvedfeeding device for cylindrical members comprising a rotatably mountedbody having means defining a member receiving opening therein, aplurality of member engaging free turning drive rollers mounted forrotation with said body and positioned with respect to the openingthrough said body to engage a cylindrical member fed therethrough.

Another object of this invention is to provide an improved feedingapparatus of the type described including the combination of a drivemotor having an axially extending opening in its armature through whicha cylindrical member may freely pass and a rotary to linear actuatorincluding at least one pair of opposed rollers having the axis of therollers radially spaced from and at an angle to the axis of rotation ofthe actuator to engage the cylindrical member and move it linearly inresponse to the rotation of the actuator.

Another object of this invention is to provide an improved feedingapparatus employing the rotary to linear motion actuator as describedabove wherein the means for driving the actuator is axially aligned withthe actuator, thus providing feeding apparatus of small cylindricaldimensions.

Another object of this invention is to provide an improved rotary tolinear actuator for feeding cylindrical members, such as wire, of thetype described wherein a pair of opposed inclined rollers are carried byarms pivotally mounted to a rotating body, one end of each arm includingcentrifugal weights which will force the rollers into positiveengagement with the member as the body is rotated to impart linearmotion to the memher.

It is another object of this invention to provide an improved apparatusfor moving a cylindrical member of the type described including biasingmeans for urging the roller against the member at low rotational speedsof the apparatus in one embodiment, each roller supporting arm ismounted on the body by a torsion bar which is arranged to preload andurge the roller into engagement with the member. In another embodiment,springs preload the rollers into positive contact with the member. It isa further object of this invention to provide a feeding mechanism of thetype described which is selfthreading, that is, which readily acceptsand thereafter moves a cylindrical member fed into the actuator.

Another object of this invention is to provide an im proved apparatusfor moving wire, particularly for moving welding or filler wire throughsubstantial lengths of cable while maintaining the wire in tension bydesigning or operating the wire feeding mechanism located closest to thesource of wire to move the wire at a slightly slower speed than thosewire feeding mechanisms located further from the wire source.

Another object of this invention is to provide an improved apparatus formoving wire, especially small diameter and/or low tensile strengthwires, wherein a pair of rotary to linear actuators are rotated inopposite directions, but move the wire in the same direction, toeliminate any tendency for the wire to twist.

Another object of this invention is to provide a novel rotary to linearactuator wherein the pulling force for moving a wire can be increased byadding additional pairs of mutually opposed, inclined rollers, whilemaintaining the contact force of the rollers against the wires belowthat which would cause damage or substantial yielding of the wiresurface.

Another object of this invention is to provide an improved welding gunof the type described in which the inert gas used for welding isdirected around the motor to cool it and around the rotary to linearactuators to assist in removing wire surface contaminates carried by thewire into the welding. gun.

Other objects and advantages of the invention will be apparent from thefollowing description, the accompanying drawings and the appendedclaims.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a generally schematic viewshowing a weld ing gun and a wire feeding device located intermediatelyof a substantial length of conduit utilizing the wire feeding apparatusof this invention.

FIG. 2 is a view, partly in cross section, showing the wire feedingapparatus of this invention contained in a spot welding gun;

FIG. 3 is a cross sectional view taken along line 33 in FIG. 2;

FIG. 4 is a view of a gas diffuser used in the embodiment of FIG. 3;

FIG. 5 is an end view of an end connector for inert gas, welding currentand motor power for use in the embodiment of FIG. 3;

FIG. 6 is an enlarged view of a wire feeding assembly employing twopairs of mutually opposed rollers;

FIG. 7 is a view of the wire feeding assembly taken along line 77 inFIG. 6;

FIG. 8 is another view of the wire feeding assembly taken along line 8-8in FIG. 6;

FIG. 9 is a view of another embodiment showing an alternate placement ofbiasing springs relative to the roller supporting arms;

FIG. 10 is a view showing the body member of the wire feeding assemblyof this invention and one of the supporting bearings for mounting theassembly in a welding gun;

FIG. 11 is a view showing particularly an inclined roller and itsrelation to the actuator body member;

FIG. 12 is a perspective view of a roller supporting arm and centrifugal,weight;

FIG. 13 is a view of the roller carrying arm showing particularly a slotformed therein;

FIG. 14 is a diagrammatic view showing the relationship of the wireengaging rollers to each other and to the welding wire;

FIGS. 15a-15c show various cross sectional configurations of rollerswhich may be used in this invention;

FIG. 16 is a pictorial view showing an embodiment of the roller carryingarm and centrifugal weight when the roller is inclined in the oppositedirection;

FIG. 17 is an end view of another embodiment of the invention wherein atorsion bar is employed to mount the roller carrying arms on the body;

FIG. 18 is a side view showing the relationship of the torsion bar tothe body and to the roller carrying arms;

FIG. 19 is a cross sectional view taken along lines 19-19 of FIG. 18;

FIG. 20 is an end view of a portion of an actuator.

showing another embodiment of the invention wherein each arm ispivotally mounted to the body by a torsion bar;

FIG. 21 is a cross sectional view taken along line 21-21 in FIG. 20;

FIG. 22 is a view showing four pairs of mutually opposed inclinedrollers mounted on a single body member;

FIG. 23 is a view showing an alternative embodiment wherein a singlemotor rotates two rotary to linear actuators in opposite directions andwherein the rollers of one actuator are inclined in a direction oppositeof the rollers of the other actuator in order to eliminate any tendencyfor twisting the wire as it it moved linearly through the actuator; and

FIG. 24 is a view, partly in cross section, of a spot welding gunwherein the rotary to linear actuators run continuously and wiremovement controlled by wire gripping means.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to thedrawings, the wire moving apparatus of this invention may be included ineither a hand held welding gun or a booster or intermediate wire movingassembly 12 located between the hand held gun 10 and a reel of weldingwire 14, as shown in FIG. 1. Welding wire is moved through a cable 17which is also adapted to carry'shielding gas and electri' cal current tothe welding gun 10. The wire and the gas is directed under the controlof an operator through a nozzle18 to a workpiece 20.

The operatorcontrols the flow of gas and the welding wire by a manuallyactuated switch 22 carried by the gun 10. This switch maybe connected toa remotely located control box 25 by wires carried in the cable. 17. Thecontrol box 25 regulates the flow of gas from a gas source 26 and theapplication of electrical current to the gun 10 through hose 27 and wire28, respectively.

As shown in FIG. 1, the wire moving apparatus of this invention is usedin the hand held gun 10 to draw wire from cable 17 and to direct thewire through nozzle 18 to the workpiece. In those welding situationswhere the distance between the gun 10 and the wire source 14 exceeds thecapacity of the wire moving apparatus, a booster 12 is used to pull thewire off the reel 14 and to assist in the movement of the wire throughcable 17 to the hand held gun 10. When using the preferred embodiment ofthe invention, as will be described, the maximum length of cable 17which may be used without one or more booster units 12. is approximately8 feet. By designing the wire moving apparatus so that substantially noyielding of the wire surface occurs, the booster 12 may be operatedcontinuously, if desired, even though the wire may be stalled sinceslippage between the wire and the wire moving mechanism of thisinvention does substantially no damage to the wire of the type whichmight cause welding problems.

The wire moving apparatus of this invention may be used in many devices,such as the hand held gun 10, the intermediate wire moving assembly orbooster 12, and

a spot welding gun 30. The spot welding gun in FIG. 2 i includes anozzle 31 which is designed to receive and direct shielding gas to thearea being welded on the workpiece. Welding wire is directed to theworkpiece through an electrically conductive guide tube 32 locatedcentrally in the nozzle 31. The details of the wire guide and nozzleform nopart of the present invention, however, no electrical currentflows through the welding wire 15 until it exits from the wire guide 32since current is applied through the guide to the wire through a slidingconnector.

The wire feeding apparatus of this invention includes two rotary tolinear actuators 35 and 36 which are rotated simultaneously by anelectric motor 37. It is to be understood that hydraulic or pneumaticmotors could also be used if desired. The rotary to linear actuators 35and 36 and the motor 37 are provided with axially extending openingsthrough which the welding wire is moved toward and through the wireguide 32.

One end of each rotary to linear actuator 35 and 36 is attached to thearmature or rotor shaft 38 of motor 37. The other end of each actuatoris supported by bearings 41, and these bearings are carried by supportdisks 43. As shown in FIG. 5, each disk 43 includes a plurality of holes44 surrounding the bearing 41, and these slots provide a passageway forshielding gas to pass around the bearing, through the gun, and into thenozzle where it is then directed over the weld.

The motor 37 is supported withinl the gun 30 in a slotted cylindricalinner casing 45 formed in two sections to facilitate assembly of thegun. Disks 43 are surrounded by a cushioning material 46, such asrubber, and are also supported within the gun by the inner casing 45. ASshown in FIG. 2, the inner'casing 45 is pro vided with a plurality oflongitudinally extending slots 47, the length of which exceeds thelength of the motor in order to provide a passageway around the motorfor the shielding gas. The entire gun 30 is enclosed with an insulatingcylindrical tube which not only protects the mechanism within the gunbut also provides electrical insulation and protection to theoperator.

The gun 30 includes an electrically conductive metallic connectorlocated within the cylindrical tube 50 to receive shielding gas, weldingwire, control wires, and electrical current from the cable 17. Theconnector 55 may be formed integrally with the lower half of the casing45. Electrical current from cable 17 flows through the connector 55 andcasing 45 around the motor and into the wire guide 32.

The connector 55 is provided with a central opening 56 through which thewelding wire may pass into the interior of the gun, and a plurality ofsmaller openings 57, 58 and 59. A threaded exterior 60 on the connector55 receives the threaded connection 61 of the cable 17.

A gas diffuser element 63 is interposed between the supporting disk 43and the connector 55 and is provided with a plurality of openings 64 and65. Openings 65 are aligned with the openings 59 and support electricalpins 66 which extend through the connector 55 to the exterior of the gunhousing. In the preferred embodiment, four such pins are employed andare used for the control of the speed of motor 37. These pins may alsobe connected to control switches, such as switch 22 shown in FIG. 1. Theconnector pins are insulated from the metallic connector 55 by epoxyfilling the openings 59.

The openings 64 communicate with a recess 68 formed in the diffuserelement 63, and shielding gas which passes through opening 58 into therecess 68 then passes through the opening 64 in diffuser element 63 andthe holes 44 and disk 47 to the interior of the motor housing. Thisshielding gas flows around the actuator 37, through the slot 47surrounding the motor 37, around the actuator 35 and throughcorresponding openings 44 in the disk 43 at the left end of the assemblyand into the nozzle 31 where it is then directed to the weld.

The movement of the gas around the motor 37 tends to cool the motor thusallowing continuous operation of the motor under heavy loads withoutexceeding its temperature limits. The gas also flows around both rotaryto linear actuators 35 and 36 and carries any dirt or wire contaminationwhich might be dislodged by the interaction between the rotary to linearactuators and the wire passing therethrough. This flow of gas thereforeremoves these contaminates from the gun housing.

Rotary to linear actuator 35 is shown in detail in FIGS. 6 through 13and includes a mandrel or body 75 having a cylindrical right end 76, acylindrical left end 77, and a generally centrally located flange 80which is provided with a plurality of threaded holes 81. As shown inFIG. 10, the left end 77 is pressed into the bearing 41. The body 75 maybe machined or formed from either metal or from a synthetic material,such as laminated fiber. As best shown in FIG. 10, an opening oraperture 82 extends completely through the body and is coaxial with theaxis of rotation of the actuator 35. The opening 82 is sufficientlylarge to permit the largest diameter wire to be used in the embodimentshown, to pass through the actuator body without interference.

The axial opening 82 is enlarged at 83, at the right end of the body asviewed in FIG. 10, to receive the drive shaft 38 of motor 37. In thepreferred embodiment, splines prevent relative rotation between thedrive shaft 38 and the body 75. Alternatively, the drive shaft 38 couldbe secured to the body 75 by set screws. The drive shaft 38 is alsoprovided with an axially aligned opening 84 to allow the wire 15 to passthrough the motor into the opening 82 and then outwardly from theactuator 35 to the workpiece.

A pair of arcuately shaped arms 90 are pivotally attached to each sideof the flange 80 by screws 91 which are received into the threadedopenings 81. Preferably, the screws 91 are provided with shoulders whichpermit them to be tightened securely to the flange 80 while at the sametime allowing the arms 90 to pivot freely around the body of the screw.As shown in FIG. 12, each arm 90 is provided with an opening 92 which isslightly larger than the body of the screw 91.

The wire engaging roller 95 is rotatably mounted to the inwardlyextending portion 96 of each arm 90 by screws 97. These screws alsoinclude a shoulder which allows them to be tightened securely to thearms 90 without restricting the freedom of rotation of the rollers 95.Each of the inwardly extending portions 96 includes a threaded opening98 which is adapted to receive the screws 97 (FIG. 12). Of course,rivets may also be used to support the rollers 95 for rotation. The

inwardly extending portion 96 of each arm 90 also has formed there on aflat surface 99 which is perpendicular to the axis of the threadedopening 98 to permit free rotation of the roller 95.

The threaded opening 98 is therefore the axis of rotation of the rollers95 and is seen to be spaced radially outwardly from the wire 15 and isinclined at an acute angle A relative to the axis of rotation of thebody 75, as viewed in FIGS. 6 and 11. The angle A may vary from 0 to90however in the preferred embodiments, the angle is normally between 5and 45.

In the embodiment of the invention shown in the accompanying drawings,three-eighth inch rollers are used to move wire which may vary in sizefrom 0.030 to 0.080 inch. These rollers are inclined at an angle of 20when moving steel wire. This results in a linear movement of 0.039 inchper revolution for 0.035 inch wire. Therefore, at a motor speed of10,000 rpm, the I wire is moved through the actuator at 390 inches perminute. For aluminum wire, the rollers are inclined at an angle of 30with a corresponding increase in the linear speed of the wire. The angleis chosen according to the desired speed ratio between the angularvelocity of the body and the longitudinal feed rate of the wire 15. Therollers 95 on one side of the flange are arranged in mutually opposedrelation with respect to the wire 15 to prevent any unnecessarydistortion of the wire.

Thus, as the body 75 rotates, the rollers 95 will follow a helical pathon the wire 15 and since the rollers are prevented from movinglongitudinally relative to the body, a component of force will thus beimparted to the wire to move it longitudinally through the opening 82.

As shown in FIG. 14, when more than one pair of mutually opposed pairsof rollers are employed, the rollers are generally evenly spaced aroundthe wire 80. In FIG. 14, the rollers 95 are mutually and diametricallyopposed, i.e., their points of contact are perpendicular to wire 80.Rollers 95 are also mutually opposed, longitudinally spaced from therollers 95, and their points of contact with the wire are from thepoints of contact of rollers 95.

Each arm 90 includes an integrally formed arcuately shaped weight 105located on the opposite side of the pivot screw 91 from the rollers 95.As the body 82 rotates, the weights 105 will tend to move outwardly dueto centrifugal force and will therefore urge each roller into positiveengagement with the wire 15. Thus, as the rotational speed of the body75 increases, the force of the rollers 95 against the wire 15 will alsoincrease. The size and weight of the arms 90 and the weights and therotational speed of the body 75 will determine the actual force exertedby each roller on the wire 15.

Biasing means are provided to insure adequate force is applied to urgethe rollers 95 into the wire 15 at low rotational speeds of the body 75.In the embodiment shown in FIG. 7, this biasing means includes smallsprings which act to push the weights 105 outwardly. These springs alsoact to push the corresponding roller on the opposite side of the wireinto the wire. The springs 110 are received into .retaining cups 111formed in the weight 105 and cups 112 formed on the inwardly extendingportion 96. It is also contemplated that the springs could interactbetween the weights 105 and the body 75 with substantially the sameresults.

An alternative embodiment is shown in FIG. 9 and includes springs 113acting between arms 90 and the body 75. The springs are held in place byscrews 114 which also control the biasing force of the springs.

Each of the arms 90 is also provided with a slot 115 positioned oppositeto roller of the complementary arm on the same side of the flange 80.This slot provides a relief and permits any accumulation of wire coatingcompound which may be removed by interaction of the wire with therollers 95 to be thrown outwardly and away from'the actuator 35. Thisprevents a buildup of dirt and prevents interference between a roller 95and the weight 105 on the adjacent arm. Movement of inert gas around theactuators also aids in removing this dirt.

The body 75, as shown in FIG. 10, is formed or machined with a slot 120having sufficient width to accommodate the rollers 95 and a depth suchthat the opening 82 through the center of the body is exposed. A slot121 is also provided to accommodate the shaft of the milling tool whichforms the opening 120, if this machining process is used, and toaccommodate the screw 97 which holds the roller 95 in place. The depthat which the slot 120 is cut depends in part upon the range of wiresizes which are to be accommodated by any particular actuator 35, itbeing desired that there be no interference between the roller 95 andthe body 75 when feeding wires of the smallest diameter is contemplated.

FIG. shows the cross sectional configuration of rollers which may beused with this invention. FIG. 15a is the roller configuration used v inthe preferred embodiment in that it allows the wire 15 to be easilyinserted into and through the actuator since the wire may cam the rolleroutwardly against the biasing means. The roller shown in FIG. 15b has anarrow contact area and may be used in those situations where highforces per unit area against the wire are desired. The rollerconfiguration of FIG. 150 has also been used with the rotary to linearactuators of this invention and give two points of contact for eachroller. A tungsten carbide roller surface is preferred due to its wearcharacteristics.

Another embodiment of the invention is shown in FIGS. 17 through 19wherein the means for biasing the rollers into frictional engagementwith the wire 15 ineludes torsion bar 140 extending through opening 141in flange 80. In FIGS. 17 and 18, only one arm on either side of theflange 80 is shown for the purpose of clarity in illustration. It is tobe understood, however, that the complementary arms on both sides of theflange will also be installed.

In this embodiment, torsion bar 140 pivotally supports arms 90 locatedon either side of the flange 80 and is rigidly, secured to each arm, butnot to the flange 80. The torsion bar is providedwith knurled or splineson each end which are forced into openings 92 in the arms of 90.. Thetorsion bar 140 is encircled by a cylinder 142 where the torsion barpasses through the flange 80 in the opening 141, and the torsion bar andthe two roller supporting arms 90 are held in the opening 141 by a ring145 which completely encircles the flange.

As the wire 15 is moved through the central opening 82 in the body 75,the rollers 95 on opposite sides of the flange which are supported bythe arms carried by one torsion bar 140 will be urged outwardly by thewire and will therefore cause the torsion bar to twist. Of course, thetwist of the torsion bar is designed to be less than the yield strengthof the material from which the torsion bar is made. Typically, a fivedegree deflection will be all that is needed in order to applysufficient biasing to the rollers to assist in moving the wire 15 at lowrotational speeds of the body 75.

Another embodiment of the invention wherein a torsion bar is used as thepivotal support for the arm 90 is shown in FIGS. 20 and 21. In thisembodiment, flange is provided with an opening 147 which receives thetorsion bar 150. The torsion bar has a large diameter section 151 nearits head which is splined and received into the opening 147 and isprevented from moving relative to the flange 80 by the splines. A reduced section 152 is allowed to move freely within the opening 147, anda further reduced section 155 is forced into a smaller opening 156 inthe arm and is also prevented from movement relative to the arm bysplines. Thus, one end of the torsion bar is secured to the flange 80and its other end is secured tothe arm 90. In this embodiment, it istherefore necessary to rotate the roller toward the wire by whateveramount is necessary to result in sufficient biasing force against thewire for movement at low rotational speeds.

As previously mentioned, the force per unit area on the wire must becontrolled in order to prevent damage to the wire as it moves throughthe rotary to linear actuators,'although some yielding of the wiresurface at the point of contact with the inclined rollers is desirablein some applications since it improves the resulting pulling force overthat achieved by friction alone. With some wires of low tensilestrength, such as aluminum, it is desirable to distribute the forcesacting on the wire in order to provide the necessary pulling force. Thiscan be donein several ways, such as by providing a plurality ofactuators 35 as described above, or by providing a single actuatorhaving more than two pairs of actuators mounted thereon. FIG. 22 showsone actuator body 160 which is provided with four pairs of mutuallyopposed rollers.

For small diameter wire, e.g., 0.020 inch and smaller, and with wires oflow tensile strength, e.g., soft alumi' num or non-heat treatedmagnesium, there is a tendency for the rotation of the actuator to twistthe wire. To eliminate this twisting tendency, the apparatus shown inFIG. 23 may be used. Here, two rotary to linear actuators are rotated inopposite directions by a motor which is mechanically connected to theactuators 171 and 172 through a gear assembly 175. The rollers in theactuator 171 are inclined relative to the wire in a direction oppositeto the inclination of the rollers in actuator 172 so that the wire willmove in the same direction, from right to left, as viewed in FIG. 23,through the welding gun even though the actuators are rotating inopposite directions.

FIG. 16 shows an arm 90 which hasmounted thereon a roller 95 which isinclined in a direction opposite to a roller mounted on the arm shown inFIG. l2..0f course, the body design and particularly the orientation ofthe slots 120 and 121 in'the body must be modified in order toaccommodate this roller orientation. Of course, the body 75 would thenhave to be rotatedin the opposite direction in order to move the wirelinearly in the same direction.

In a spot welding application where accurate control of the wiremovement is required, it is desirable to eliminate the inertial effectsin starting and stopping the linear actuator and motor used to drive theactuators. Since no substantial damage to the wire occurs while it isstalled, even though the actuators continue rotating,

accurate control over the movement of the wire may be obtained byincluding wire gripping means, such as a solenoid brake, to control themovement of the wire while allowing the actuators to rotatecontinuously. One embodiment of the invention using this principle isshown in FIG. 24. Here, wire 15 is directed through rotary to linearactuators 35 and 36, and a timer controlled solenoid brake 180 controlsthe movement of the wire. The actuator motor 37 is supplied with powerthrough a constant voltage source 181 and rotates the actuatorscontinuously. A timer 185 allows movement of the wire for predeterminedperiods of time, either automatically or under the direction of aseparate control circuit 186. For example, the timer 185 may allow thewire to move for 0.4 second at six second intervals or for 0.4 secondeach time a trigger pulse is generated by the control circuit 186.Accurate movement of the wire through small distance increments istherefore provided by this arrangement.

It is desired, the number of inclined rollers acting on the wire may beincreased and the biasing force of the rollers against the wire reducedto maintain the same moving force to the wire. This will result inless'yielding of the wire surface while premitting the same moving forceto be generated and is preferred in those applications, e.g., booster orspot welding gun, where the wire may be allowed to stall.

Thus, a rotary to linear actuator has been described which employscentrifugal weights to urge inclined rollers into frictional engagementwith the wire which is then moved longitudinally ,as the rollers arerotated about the wire. Also, an improved welding gun or other wirefeeding apparatus has been described which in cludes a motor having acentral opening extending axially therethrough to rotate the rotary tolinear actuators. Such coaxial construction permits fabrication ofwelding guns and wire feeding' mechanisms having small cross sectionalareas. The inclined rollers may be biased against the wire by springs orby torsion bars.

While the forms of apparatus herein described constitute preferredembodiments of the invention, it is to be understood that the inventionis not limited to these forms of apparatus, and that changes may be madetherein without departing from the scope of the invention which isdefined in the appended claims.

What is claimed is:

l. A wire moving device comprising actuator means for moving a wire in alinear direction as said actuator means is rotated about the wire; saidactuator means including a body having an axis about which it may berotated;

means defining an axially extending opening in said body through whichwire may pass;

at least one roller mounted on said body for rotation therewith, theaxis of said roller being at a fixed inclination relative to the axis ofsaid body, said roller engaging the wire to impart thereto a linearcomponent of force as said body and said roller are rotated; and

brake means for gripping said wire to control movement in a lineardirection through said actuator means while said actuator means rotatescontinuously about the wire thereby providing for accurate control ofwire movement.

2. The wire moving device of claim 1 wherein said actuator means furtherincludes an arm mounted on said body for supporting said roller; and

a centrifugal weight on said arm which, as the body is rotated, acts tocounterbalance at least the centrifugal force acting on said roller assaid body is rotated.

3. The wire moving device of claim 1 wherein said means for rotatingsaid body includes an electric motor having an armature connected torotate said body, and means forming an axially extending opening throughsaid armature concentric with the opening in said body through whichwire may pass.

4. The wire moving device of claim 1 wherein said means for grippingsaid wire includes a solenoid brake which controls the movement of saidwire in a linear direction while said actuator means rotatescontinuously.

5. The wire moving device of claim 1 further including an electric motorfor rotating said actuator means and a constant voltage source forsupplying power to said electric motor to rotate said actuatorcontinuously at a substantially constant speed.

6. The wire moving device of claim 1 for use in spot welding whereinsaid actuator means rotates about said wire continuously, said rollerhaving an outer circumferential surface which engages the wire and whichcauses no substantial damage to the wire while the linear motion of thewire is restricted by said brake means.

7. The wire moving device of claim 6 wherein said brake means includes asolenoid brake, said device further including timer means for releasingsaid brake for predetermined periods of time to move predeterminedincrements of wire through said device during each cycle of operation.

8. A wire moving device comprising a body having an axially extendingopening through which wire may pass,

at least two rollers mounted on said body for'rotation therewith, theaxis of each roller being inclined relative to teh axis of said body,said rollers engaging the wire to impart thereto a component of force tomove the wire axially as said body and said rollers are rotated,

means mounted for rotation with said body for supporting each of saidrollers and including centrifugal weights which act against thecentrifugal force on said rollers as said body and rollers are rotatedto hold said rollers in engagement with the wire, and

brake means for gripping said wire to restrain its movement in the axialdirection while said body continues to rotate about the wire thereby toprovide for accurate control of wire movement.

1. A wire moving device comprising actuator means for moving a wire in alinear direction as said actuator means is rotated about the wire; saidactuator means including a body having an axis about which it may berotated; means defining an axially extending opening in said bodythrough which wire may pass; at least one roller mounted on said bodyfor rotation therewith, the axis of said roller being at a fixedinclination relative to the axis of said body, said roller engaging thewire to impart thereto a linear component of force as said body and saidroller are rotated; and brake means for gripping said wire to controlmovement in a linear direction through said actuator means while saidactuator means rotates continuously about the wire thereby providing foraccurate control of wire movement.
 2. The wire moving device of claim 1wherein said actuator means further includes an arm mounted on said bodyfor supporting said roller; and a centrifugal weight on said arm which,as the body is rotated, acts to counterbalance at least the centrifugalforce acting on said roller as said body is rotated.
 3. The wire movingdevice of claim 1 wherein said means for rotating said body includes anelectric motor having an armature connected to rotate said body, andmeans forming an axially extending opening through said armatureconcentric with the opening in said body through which wire may pass. 4.The wire moving device of claim 1 wherein said means for gripping saidwire includes a solenoid brake which controls the movement of said wirein a linear direction while said actuator means rotates continuously. 5.The wire moving device of claim 1 further including an electric motorfor rotating said actuator means and a constant voltage source forsupplying poweR to said electric motor to rotate said actuatorcontinuously at a substantially constant speed.
 6. The wire movingdevice of claim 1 for use in spot welding wherein said actuator meansrotates about said wire continuously, said roller having an outercircumferential surface which engages the wire and which causes nosubstantial damage to the wire while the linear motion of the wire isrestricted by said brake means.
 7. The wire moving device of claim 6wherein said brake means includes a solenoid brake, said device furtherincluding timer means for releasing said brake for predetermined periodsof time to move predetermined increments of wire through said deviceduring each cycle of operation.
 8. A wire moving device comprising abody having an axially extending opening through which wire may pass, atleast two rollers mounted on said body for rotation therewith, the axisof each roller being inclined relative to teh axis of said body, saidrollers engaging the wire to impart thereto a component of force to movethe wire axially as said body and said rollers are rotated, meansmounted for rotation with said body for supporting each of said rollersand including centrifugal weights which act against the centrifugalforce on said rollers as said body and rollers are rotated to hold saidrollers in engagement with the wire, and brake means for gripping saidwire to restrain its movement in the axial direction while said bodycontinues to rotate about the wire thereby to provide for accuratecontrol of wire movement.